How hard or easy is it to remove the side panniers on a touring S? My riding friend has a V-strom & when he "quick detaches" his panniers it leaves ugly brackets.. Same with MTS? So he never ever rides without them attached.

Panniers come off easy enough, and the mounting points are pretty tightly integrated into the bodywork, unlike the scaffolding that is typical of most ADV bikes.

In the pic below, notice the pannier locking latch just behind the pillion footpeg hanger, and the two notches in the black plastic of the tail section, that's pretty much it.